trigger DeleteMeetingReport on MeetingReport__c (before delete) {

	List<String> meetingIds = new List<String>();
	
	for (MeetingReport__c mr : trigger.old) {
		meetingIds.add(mr.Id);
	}
	
	delete [Select Id From MeetingAttendees__c Where Meeting_Report__c in :meetingIds];
	delete [Select Id From MeetingInvitees__c Where Meeting_Report__c in :meetingIds];
	delete [Select Id From MeetingFile__c Where Meeting_Report__c in :meetingIds];
}